Objectives:
It is recommended that the intra-articular component of a supracondylar distal femoral fracture be stabilized by a lag screw to create interfragmental compression. Generally, it is thought that lag screw fixation should precede any positional screw or locking screw application. This study compared 3 methods of maintaining interfragmentary compression after fracture reduction with a reduction clamp.
Methods:
Intra-articular vertical split fractures were created in synthetic femora. A force transducer was interposed between the medial and lateral condyles and 20 lbs of compression was applied to the fracture with a reduction clamp. 3.5-mm cortical lag screws (group 1), 3.5-mm cortical position screws (group 2), and 5.4-mm distal locking screws through a distal femur locking plate (group 3) were placed across the fracture (n = 4/group). After screw placement, the clamp was removed and the amount of residual interfragmentary compression was recorded. After 2 minutes, a final steady-state force was measured and compared across groups.
Results:
Locking screws placed through the plate (group 3) maintained 27% of the initial force applied by the clamp (P = 0.043), whereas positional screws (group 2) maintained 90% of the initial force applied by the clamp (P = 0.431). The steady-state compression force measured with lag screws (group 1) increased by 240% (P = 0.030) relative to the initial clamp force. The steady-state force in the lag screw group was significantly greater than groups 1 and 2 (P = 0.012).
Conclusions:
When reducing intra-articular fractures and applying interfragmentary compression with reduction clamps, additional lag screws increase the amount of compression across the fracture interface. Compressing a fracture with reduction clamps and relying on locking screws to maintain the compression result in a loss of interfragmentary compression and should be avoided. This study lends biomechanical support that lag screws placed outside of the plate before locking screws for fracture fixation help maintain optimal interfragmentary compression.
We believe that the carpal shoot-through view has utility and can be implemented to augment standard intraoperative views, and may decrease the incidence of screw protrusion resulting in soft tissue injuries.
Objective:
To compare the efficacy of 2 intertrochanteric (IT) fracture fixation devices in conferring mechanical stability to unstable IT femur fractures.
Methods:
Nine pairs of cadaveric female femurs with a groupwise average bone quality indicative of osteopenia were used. An unstable IT fracture without calcar support (OTA/AO 31-A2) was created and stabilized with either a sliding hip screw and side plate (SHS) or a cephalomedullary nail using an integrated dual-screw fixation [InterTAN (ITN)]. Constructs were evaluated under stepwise and increasing cyclic loading up to 50,000 cycles (1500 N) or by failure in a test model that may best simulate hip joint contact forces at heel strike. Number of cycles to failure, failure load, and femoral head rotation about the screw axis were compared between groups.
Results:
The average number of cycles in the ITN group was greater compared with that in the SHS group (48,383 vs. 31,403 cycles, P = 0.046). Similarly, the average maximum load survived by the ITN group was greater than that of the SHS group (1456 vs. 1113 N, P = 0.046). The number of constructs that survived up to the maximum applied load of 1500 N was greater in the ITN group (8/9, 89%) when compared with that of the SHS constructs (3/9, 33%) (P = 0.049). Finally, the ITN group conferred greater rotational control of the femoral head compared with the SHS constructs (1.5 vs. 5.5 degrees, P = 0.018), and reduced the amount of varus collapse (11.1 vs. 31.1 degrees, P = 0.038).
Conclusions:
The integrated dual-screw construct appeared to confer significantly greater fracture stability compared with a sliding hip screw and side plate using a worst-case model that simulates heel strike during gait. Study data provide biomechanical evidence that the ITN device may provide more stability and rotational resistance than a sliding hip screw in the elderly female patient population with an unstable IT fracture and compromised bone quality.
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